<?php

    /**
     * PHPExcel_Reader_Excel5_MD5
     * Copyright (c) 2006 - 2015 PHPExcel
     * This library is free software; you can redistribute it and/or
     * modify it under the terms of the GNU Lesser General Public
     * License as published by the Free Software Foundation; either
     * version 2.1 of the License, or (at your option) any later version.
     * This library is distributed in the hope that it will be useful,
     * but WITHOUT ANY WARRANTY; without even the implied warranty of
     * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
     * Lesser General Public License for more details.
     * You should have received a copy of the GNU Lesser General Public
     * License along with this library; if not, write to the Free Software
     * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
     * @category   PHPExcel
     * @package    PHPExcel_Reader_Excel5
     * @copyright  Copyright (c) 2006 - 2015 PHPExcel (http://www.codeplex.com/PHPExcel)
     * @license    http://www.gnu.org/licenses/old-licenses/lgpl-2.1.txt        LGPL
     * @version    ##VERSION##, ##DATE##
     */
    class PHPExcel_Reader_Excel5_MD5 {
        // Context
        private $a;
        private $b;
        private $c;
        private $d;

        /**
         * MD5 stream constructor
         */
        public function __construct() {
            $this->reset();
        }

        /**
         * Reset the MD5 stream context
         */
        public function reset() {
            $this->a = 0x67452301;
            $this->b = 0xEFCDAB89;
            $this->c = 0x98BADCFE;
            $this->d = 0x10325476;
        }

        private static function f($X, $Y, $Z) {
            return (($X & $Y) | ((~$X) & $Z)); // X AND Y OR NOT X AND Z
        }

        private static function g($X, $Y, $Z) {
            return (($X & $Z) | ($Y & (~$Z))); // X AND Z OR Y AND NOT Z
        }

        private static function h($X, $Y, $Z) {
            return ($X ^ $Y ^ $Z); // X XOR Y XOR Z
        }

        private static function i($X, $Y, $Z) {
            return ($Y ^ ($X | (~$Z))); // Y XOR (X OR NOT Z)
        }

        /**
         * Get MD5 stream context
         * @return string
         */
        public function getContext() {
            $s = '';
            foreach ([
                         'a',
                         'b',
                         'c',
                         'd'
                     ] as $i) {
                $v = $this->{$i};
                $s .= chr($v & 0xff);
                $s .= chr(($v >> 8) & 0xff);
                $s .= chr(($v >> 16) & 0xff);
                $s .= chr(($v >> 24) & 0xff);
            }
            return $s;
        }

        /**
         * Add data to context
         * @param string $data Data to add
         */
        public function add($data) {
            $words = array_values(unpack('V16', $data));
            $A = $this->a;
            $B = $this->b;
            $C = $this->c;
            $D = $this->d;
            $F = [
                'PHPExcel_Reader_Excel5_MD5',
                'f'
            ];
            $G = [
                'PHPExcel_Reader_Excel5_MD5',
                'g'
            ];
            $H = [
                'PHPExcel_Reader_Excel5_MD5',
                'h'
            ];
            $I = [
                'PHPExcel_Reader_Excel5_MD5',
                'i'
            ];
            /* ROUND 1 */
            self::step($F, $A, $B, $C, $D, $words[0], 7, 0xd76aa478);
            self::step($F, $D, $A, $B, $C, $words[1], 12, 0xe8c7b756);
            self::step($F, $C, $D, $A, $B, $words[2], 17, 0x242070db);
            self::step($F, $B, $C, $D, $A, $words[3], 22, 0xc1bdceee);
            self::step($F, $A, $B, $C, $D, $words[4], 7, 0xf57c0faf);
            self::step($F, $D, $A, $B, $C, $words[5], 12, 0x4787c62a);
            self::step($F, $C, $D, $A, $B, $words[6], 17, 0xa8304613);
            self::step($F, $B, $C, $D, $A, $words[7], 22, 0xfd469501);
            self::step($F, $A, $B, $C, $D, $words[8], 7, 0x698098d8);
            self::step($F, $D, $A, $B, $C, $words[9], 12, 0x8b44f7af);
            self::step($F, $C, $D, $A, $B, $words[10], 17, 0xffff5bb1);
            self::step($F, $B, $C, $D, $A, $words[11], 22, 0x895cd7be);
            self::step($F, $A, $B, $C, $D, $words[12], 7, 0x6b901122);
            self::step($F, $D, $A, $B, $C, $words[13], 12, 0xfd987193);
            self::step($F, $C, $D, $A, $B, $words[14], 17, 0xa679438e);
            self::step($F, $B, $C, $D, $A, $words[15], 22, 0x49b40821);
            /* ROUND 2 */
            self::step($G, $A, $B, $C, $D, $words[1], 5, 0xf61e2562);
            self::step($G, $D, $A, $B, $C, $words[6], 9, 0xc040b340);
            self::step($G, $C, $D, $A, $B, $words[11], 14, 0x265e5a51);
            self::step($G, $B, $C, $D, $A, $words[0], 20, 0xe9b6c7aa);
            self::step($G, $A, $B, $C, $D, $words[5], 5, 0xd62f105d);
            self::step($G, $D, $A, $B, $C, $words[10], 9, 0x02441453);
            self::step($G, $C, $D, $A, $B, $words[15], 14, 0xd8a1e681);
            self::step($G, $B, $C, $D, $A, $words[4], 20, 0xe7d3fbc8);
            self::step($G, $A, $B, $C, $D, $words[9], 5, 0x21e1cde6);
            self::step($G, $D, $A, $B, $C, $words[14], 9, 0xc33707d6);
            self::step($G, $C, $D, $A, $B, $words[3], 14, 0xf4d50d87);
            self::step($G, $B, $C, $D, $A, $words[8], 20, 0x455a14ed);
            self::step($G, $A, $B, $C, $D, $words[13], 5, 0xa9e3e905);
            self::step($G, $D, $A, $B, $C, $words[2], 9, 0xfcefa3f8);
            self::step($G, $C, $D, $A, $B, $words[7], 14, 0x676f02d9);
            self::step($G, $B, $C, $D, $A, $words[12], 20, 0x8d2a4c8a);
            /* ROUND 3 */
            self::step($H, $A, $B, $C, $D, $words[5], 4, 0xfffa3942);
            self::step($H, $D, $A, $B, $C, $words[8], 11, 0x8771f681);
            self::step($H, $C, $D, $A, $B, $words[11], 16, 0x6d9d6122);
            self::step($H, $B, $C, $D, $A, $words[14], 23, 0xfde5380c);
            self::step($H, $A, $B, $C, $D, $words[1], 4, 0xa4beea44);
            self::step($H, $D, $A, $B, $C, $words[4], 11, 0x4bdecfa9);
            self::step($H, $C, $D, $A, $B, $words[7], 16, 0xf6bb4b60);
            self::step($H, $B, $C, $D, $A, $words[10], 23, 0xbebfbc70);
            self::step($H, $A, $B, $C, $D, $words[13], 4, 0x289b7ec6);
            self::step($H, $D, $A, $B, $C, $words[0], 11, 0xeaa127fa);
            self::step($H, $C, $D, $A, $B, $words[3], 16, 0xd4ef3085);
            self::step($H, $B, $C, $D, $A, $words[6], 23, 0x04881d05);
            self::step($H, $A, $B, $C, $D, $words[9], 4, 0xd9d4d039);
            self::step($H, $D, $A, $B, $C, $words[12], 11, 0xe6db99e5);
            self::step($H, $C, $D, $A, $B, $words[15], 16, 0x1fa27cf8);
            self::step($H, $B, $C, $D, $A, $words[2], 23, 0xc4ac5665);
            /* ROUND 4 */
            self::step($I, $A, $B, $C, $D, $words[0], 6, 0xf4292244);
            self::step($I, $D, $A, $B, $C, $words[7], 10, 0x432aff97);
            self::step($I, $C, $D, $A, $B, $words[14], 15, 0xab9423a7);
            self::step($I, $B, $C, $D, $A, $words[5], 21, 0xfc93a039);
            self::step($I, $A, $B, $C, $D, $words[12], 6, 0x655b59c3);
            self::step($I, $D, $A, $B, $C, $words[3], 10, 0x8f0ccc92);
            self::step($I, $C, $D, $A, $B, $words[10], 15, 0xffeff47d);
            self::step($I, $B, $C, $D, $A, $words[1], 21, 0x85845dd1);
            self::step($I, $A, $B, $C, $D, $words[8], 6, 0x6fa87e4f);
            self::step($I, $D, $A, $B, $C, $words[15], 10, 0xfe2ce6e0);
            self::step($I, $C, $D, $A, $B, $words[6], 15, 0xa3014314);
            self::step($I, $B, $C, $D, $A, $words[13], 21, 0x4e0811a1);
            self::step($I, $A, $B, $C, $D, $words[4], 6, 0xf7537e82);
            self::step($I, $D, $A, $B, $C, $words[11], 10, 0xbd3af235);
            self::step($I, $C, $D, $A, $B, $words[2], 15, 0x2ad7d2bb);
            self::step($I, $B, $C, $D, $A, $words[9], 21, 0xeb86d391);
            $this->a = ($this->a + $A) & 0xffffffff;
            $this->b = ($this->b + $B) & 0xffffffff;
            $this->c = ($this->c + $C) & 0xffffffff;
            $this->d = ($this->d + $D) & 0xffffffff;
        }

        private static function step($func, &$A, $B, $C, $D, $M, $s, $t) {
            $A = ($A + call_user_func($func, $B, $C, $D) + $M + $t) & 0xffffffff;
            $A = self::rotate($A, $s);
            $A = ($B + $A) & 0xffffffff;
        }

        private static function rotate($decimal, $bits) {
            $binary = str_pad(decbin($decimal), 32, "0", STR_PAD_LEFT);
            return bindec(substr($binary, $bits) . substr($binary, 0, $bits));
        }
    }
